PARIS -- Humans have planted trees for over 11,000 years. Evidence suggests that fig trees in the Middle East were one of the first to be grown for picking fruit. Now, trees are on the frontline of the battle against climate change.

Negotiators from over 190 countries are at the U.N. Climate Change Conference to reach an agreement on how to reduce CO2 emissions so that global temperature rise can be arrested at 2 degrees Celsius above pre-industrial levels.

Tony Simons, Director General of the World Agroforestry Centre, told HuffPost India that when trees evolved 350 million years ago, Earth's temperature was 10 degrees hotter and CO2 concentration was 10 times more than it is today.

Agroforestry is the practice of cultivating trees on agricultural land.

"Trees are wonderful. They are the largest living things, the oldest living things. Trees made the world inhabitable for humans," said Simons. "Nothing is better than a tree for sequestering carbon, nothing is better than a tree for bringing up water from depth."

But forest cover is down to 30 percent from 60 percent after the last ice age, which ended around 11,500 years ago. In India, forest cover is around 24 percent, and the Modi government has promised to increase this to 33 percent in order to absorb 2.5 to 3 billion tonnes of CO2 by 2030.

But where will the government find 27 million hectares of land for an almost 10 percent increase in forest cover?

In his conversation with HuffPost India at COP21, Simons said that if India wants to plant more trees without taking land away from people, it would have to be on agricultural land and farms.

Simons also talked about how these trees would also allow farmers to diversify on their produce instead of banking on just one crop which could be destroyed by unseasonal rains or drought. The frequency of extreme weather events is expected to increase due to climate change.

"The future of forestry is on farms," he said.

Trees are wonderful. They are the largest living things, the oldest living things. Trees made the world inhabitable for humans

Tree planting has gone on for a long time but it's often for a few needs and not as much for cash. Fruit trees can you give that extra income. If you are a coffee farmer, you get paid once a year. If you are a cocoa farmer, you get paid once a year. There are a lot of trees that you can get a monthly return on because you are continuously picking or harvesting something. Tea is a good example of that.

We know with climate change, extreme events are occurring more and more often. It takes very long for people to adjust. So if one of your enterprises fails then you need two or three others. We don't want farmers committing suicide, we don't want farmers to sell their land or move to slums and cities.

How is planting trees near agricultural fields better than just planting trees when it comes to combating climate change?

The ability of those fields (with trees) to absorb high temperatures or water stress if you get drought or flooding. When you have more organic matter in the soil, it will hold water for longer. During the dry season, trees have leaves which you can feed to goats, cows and buffaloes to keep them alive.

We talk about a 2 degrees climate change, the drop in temperature under the shade of a tree is somewhere between 4 and 6 degrees.

If you plant a big eucalyptus forest of a thousand hectares and you have a fire, you lose the lot. If you have the same trees planted in 10,000 fields, you have 10,000 fire fighters. So it's putting that management and the benefit of trees back into the hands of the people.

The drop in temperature under the shade of a tree is somewhere between 4 and 6 degrees.

India plans to increase its forest cover from to 24 to 33 percent to absorb CO2 as part of its national action plan to counter climate change. Where is the space for these trees?

That is about 27 million hectares of land and it is not going to be recreating natural forests and there isn't too much degraded forest to rehabilitate. It's going to be in agricultural fields and agricultural lands.

The importance of those trees is also in terms of recycling water, providing shade, and making those environments more resilient to climate change. Trees put a lot of organic matter into the soil and that organic carbon is what puts sand and silt and clay together. It takes 100 years to build up a single layer of top soil and you can lose that in a single rainfall event. So when it rains, you want your soil to be a sponge, not a sieve.

It is a triple win of trying to increase production, trying to reduce emissions, and trying to adapt to the changing climate. In very simple terms, climate smart agriculture is trying to simultaneously intensify and diversify agriculture production.

Is climate smart agriculture already practiced in India?

It is in a way. It may not be called climate-smart. Some farmers look for the multi benefit. The key problem is getting the message out. There are a lot of NGOs doing that, a lot of state extension agents. But I think the future is going to be through small scale private entrepreneurs who see an opportunity in being input providers. It will be young people. Even with urbanisation, there are still going to be 800-900 million people living in rural areas: how do we have them fully employed, how are they engaged, and how can they do things differently. I think it is an opportunity for India to turn on its head how it looks at diversifying agriculture.

We have to produce the same amount of food in the next 40 years that we have in the last 8000.

How does agroforestry help deal with climate change?

If you keep drawing out of the soil - water, organic matter - you are depleting it. Just that nature doesn't send us an invoice for all these services that it is providing. On an average around the world, the cost of production is three of four times than the agriculture produce.

Climate Change has been with us for a very long time. Just that now, the direction of change, which used to take a million years, is now happening ten or twenty times faster. And that's the problem. It's so rapid that we don't know how to respond. And we are locked into the finite amount of land that we have. We have to produce the same amount of food in the next 40 years that we have in the last 8000. It can be done more efficiently. But if we continue to rely on the four main cereals - rice, wheat, maize, and sorghum - then we will continue to struggle. The world eats too much meat.

This is about creating diversification. It's a long term change. It is not going to happen overnight. But if you're going in the wrong direction then there is going to environmental disaster.

So it's putting that management and the benefit of trees back into the hands of the people.